Field of the Invention
The present invention pertains generally to devices and methods for maintaining pipe systems wherein a section of pipe is frozen so that components may be swapped out or another section of pipe could be repaired. More particularly, the invention relates to an improved pipe freezing apparatus, and further novel methods and devices useful for replacing an angle meter stop valve.
Description of the Prior Art
Pipe freezing apparatuses, for creating a dry section of pipe to be worked on downstream relative thereto, have been known for some time. A somewhat early example was proposed by Hallett, U.S. Pat. No. 5,987,906, entitled “Pipe Freezing Apparatus,” and was awarded patent protection in 1999. Another example was developed by Ingram, U.S. Pat. No. 8,240,167 entitled “Cyrogenic Freezing Apparatus.”
As told by both Ingram and Hallett, historically, repairing or replacing sections of fluid carrying pipe required draining of the pipe, and then cutting and/or replacing the pipe section (or valve section). This time consuming and expensive procedure has been largely replaced through the use of pipe freezing devices that freeze a plug of liquid inside the pipe upstream of the pipe section that is to be repaired or replaced. The frozen plug prevents liquid from flowing from the pipe during repair. After the repairs have been made, the plug is allowed to thaw so that liquid can again flow through the pipe.
Pipe freezing devices are further typically comprised of a refrigerant chamber that is placed around or against the pipe section to be frozen. In one type of device, the chamber includes a concave wall section having a radius that corresponds to the radius of the pipe. When used, the chamber, which is of a thermally conductive material such as aluminum, is placed against the pipe.
European Patent Application, EP-A-0145114, entitled “Pipe Freezing Device,” and filed in 1984, describes a pipe freezing apparatus which is particularly suited to freezing water in pipes, enabling same to be cut without draining the system. In this particular patent disclosure, a freezer head is attached to the pipe on each side of the region to be worked on, and plugs of frozen water are formed in the pipe, at the location of the freezer heads. The freezer heads constitute expansion chambers, liquid refrigerant being pumped (or drawn) into the chamber walls. The arrangement is well known.
In another type of freezing device, commonly referred to as a pipe enclosure device, the chamber is comprised of two sections that are clamped together around the pipe. The resultant chamber has openings in each end with a cross-section corresponding to the cross-section of the pipe. The present invention relates generally to a pipe freezing apparatus of the type.
The freezing device also includes an inlet that can be connected to a source of a low-temperature liquid refrigerant, e.g. pressurized liquid CO2 or nitrogen. The chamber also includes one or more exhaust ports, to which may be coupled a vent stack, normally on the opposite side of the chamber from the refrigerant inlet.
In use, the chamber is clamped around the pipe section with the pipe extending through the openings in the chamber. Refrigerant is then introduced, normally via a hose from a refrigerant source, into the chamber and allowed to evaporate, with the evaporated refrigerant escaping through one or more of the exhaust ports. As the refrigerant solidifies into dry ice and subsequently evaporates, heat is extracted from the pipe and fluid within the section of pipe enclosed by the chamber, resulting in freezing of the liquid within the section of pipe enclosed by the chamber.
Regarding a more specific application, it is routinely common for the angle meter stop valve in a water service line to a water meter at a residence or business establishment to need replacement due to corrosion or normal wear and tear. Because the angle meter stop valve is positioned below ground level, the removal of the old angle meter stop valve is conventionally performed by digging a large hole around the angle meter stop valve so that the wrenches can be attached to the angle meter stop valve fittings and appropriately rotated. Prior to removing the angle meter stop valve, the water supply pipe leading to the angle meter stop valve is blocked by freezing the water in a region of the pipe below the angle meter stop valve. Conventionally, this is a time consuming process requiring the removal of a large amount of soil or even concrete to provide the necessary access for tools and personnel; however, the present invention seeks to provide novel tools and method making this procedure less costly and more safe to the field operator.
In a first aspect, the present invention seeks to offer improvements to a chamber-type pipe freezing apparatus. More specifically, said improvements herein are particularly useful when the pipe section to be maintained is subterranean so that a hole must be dug. Still further, the invention improves upon job safety when using CO2 (dry ice) evaporating and venting the chamber as a gas displacing oxygen. It is yet an additional object of the present invention to provide a system wherein the pipe freezing apparatus can be installed by hand without tools. It is yet still further an object of the present invention to devise a system and method that is useful for all types of pipe including; PVC, copper and cast iron. It is still an object of the present invention to obviate a need for a specifically designed vent for the pipe freezing apparatus.